refactor: add tool_error/tool_result helpers + read_raw_config, migrate 129 callsites

Add three reusable helpers to eliminate pervasive boilerplate:

tools/registry.py — tool_error() and tool_result():
  Every tool handler returns JSON strings. The pattern
  json.dumps({"error": msg}, ensure_ascii=False) appeared 106 times,
  and json.dumps({"success": False, "error": msg}, ...) another 23.
  Now: tool_error(msg) or tool_error(msg, success=False).

  tool_result() handles arbitrary result dicts:
  tool_result(success=True, data=payload) or tool_result(some_dict).

hermes_cli/config.py — read_raw_config():
  Lightweight YAML reader that returns the raw config dict without
  load_config()'s deep-merge + migration overhead. Available for
  callsites that just need a single config value.

Migration (129 callsites across 32 files):
- tools/: browser_camofox (18), file_tools (10), homeassistant (8),
  web_tools (7), skill_manager (7), cronjob (11), code_execution (4),
  delegate (5), send_message (4), tts (4), memory (7), session_search (3),
  mcp (2), clarify (2), skills_tool (3), todo (1), vision (1),
  browser (1), process_registry (2), image_gen (1)
- plugins/memory/: honcho (9), supermemory (9), hindsight (8),
  holographic (7), openviking (7), mem0 (7), byterover (6), retaindb (2)
- agent/: memory_manager (2), builtin_memory_provider (1)

plugins/memory/hindsight/__init__.py

@@ -26,6 +26,7 @@ import threading
 from typing import Any, Dict, List
 
 from agent.memory_provider import MemoryProvider
+from tools.registry import tool_error
 
 logger = logging.getLogger(__name__)
 
@@ -433,12 +434,12 @@ class HindsightMemoryProvider(MemoryProvider):
             client = self._get_client()
         except Exception as e:
             logger.warning("Hindsight client init failed: %s", e)
-            return json.dumps({"error": f"Hindsight client unavailable: {e}"})
+            return tool_error(f"Hindsight client unavailable: {e}")
 
         if tool_name == "hindsight_retain":
             content = args.get("content", "")
             if not content:
-                return json.dumps({"error": "Missing required parameter: content"})
+                return tool_error("Missing required parameter: content")
             context = args.get("context")
             try:
                 _run_sync(client.aretain(
@@ -447,12 +448,12 @@ class HindsightMemoryProvider(MemoryProvider):
                 return json.dumps({"result": "Memory stored successfully."})
             except Exception as e:
                 logger.warning("hindsight_retain failed: %s", e)
-                return json.dumps({"error": f"Failed to store memory: {e}"})
+                return tool_error(f"Failed to store memory: {e}")
 
         elif tool_name == "hindsight_recall":
             query = args.get("query", "")
             if not query:
-                return json.dumps({"error": "Missing required parameter: query"})
+                return tool_error("Missing required parameter: query")
             try:
                 resp = _run_sync(client.arecall(
                     bank_id=self._bank_id, query=query, budget=self._budget
@@ -463,12 +464,12 @@ class HindsightMemoryProvider(MemoryProvider):
                 return json.dumps({"result": "\n".join(lines)})
             except Exception as e:
                 logger.warning("hindsight_recall failed: %s", e)
-                return json.dumps({"error": f"Failed to search memory: {e}"})
+                return tool_error(f"Failed to search memory: {e}")
 
         elif tool_name == "hindsight_reflect":
             query = args.get("query", "")
             if not query:
-                return json.dumps({"error": "Missing required parameter: query"})
+                return tool_error("Missing required parameter: query")
             try:
                 resp = _run_sync(client.areflect(
                     bank_id=self._bank_id, query=query, budget=self._budget
@@ -476,9 +477,9 @@ class HindsightMemoryProvider(MemoryProvider):
                 return json.dumps({"result": resp.text or "No relevant memories found."})
             except Exception as e:
                 logger.warning("hindsight_reflect failed: %s", e)
-                return json.dumps({"error": f"Failed to reflect: {e}"})
+                return tool_error(f"Failed to reflect: {e}")
 
-        return json.dumps({"error": f"Unknown tool: {tool_name}"})
+        return tool_error(f"Unknown tool: {tool_name}")
 
     def shutdown(self) -> None:
         global _loop, _loop_thread